/*
  《Vue.js 版本飞机大战新冠病毒》
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  作者：阿峰
  网址：http://www.fongzz.com/vuejs-aircraft-fight-virus
  - - - - - - - - - - - - - - - - - - 
  2020年4月
*/ 



/* 天空 */
#sky {
  background-image: url('../assets/img/city_2.jpg');
  height: 600px;
}


/* 🛩 战斗机 */
#f {  
  position: absolute;
  font-size: xx-large;
}

/* 😷 f_bullet */
.f_bullet {  
  position: absolute;
}

/* 云 */
.cloud {
  position: absolute;
  pointer-events: none; /* 鼠标事件向下穿透 */
  z-index: 1;
  opacity: 0.9;
}

/* 新冠病毒 */
.virus {  
  position: absolute;
  pointer-events: none;
}

/* 成功按钮 */
#success_btn {
  position: absolute;
  animation-duration: 2s;
  animation-delay: 0.5s;
  animation-iteration-count: infinite;
  z-index: 5;
}